施钾对苜蓿上牛角花齿蓟马产卵选择、生长发育、 成虫寿命和繁殖力的影响

【目的】为了探讨施钾对苜蓿上牛角花齿蓟马Odontothrips loti的产卵选择、生长发育、成虫寿命和繁殖力的影响,明确施钾苜蓿叶片营养物含量与牛角花齿蓟马生命参数的关系。【方法】在不同钾量(40, 60, 80和100 mg/kg)处理下(以不施钾作为对照),观察记录牛角花齿蓟马在紫花苜蓿品种甘农3号Medicago sativa cv. Gannong No. 3叶片上的产卵量,幼期各龄期发育历期和存活率以及二代成虫的寿命和繁殖力,同时测定不同施钾量下苜蓿叶片的可溶性糖、游离氨基酸及钾含量。【结果】随着施钾量的增加,牛角花齿蓟马在苜蓿叶片上的产卵量(粒/复叶)先降低后升高,在60 mg/kg钾处理降幅最大,较对照降低了45.58%;卵孵化率和1-2龄若虫的存活率变化不显著,但3-4龄若虫的存活率和幼期总存活率显著下降,分别在100 mg/kg 和80 mg/kg钾处理下降幅最大,较对照分别下降了54.36%和48.48%。不同施钾量下苜蓿叶片上牛角花齿蓟马卵和1-2龄若虫发育历期无显著变化,3-4龄若虫及幼期总发育历期均延长;牛角花齿蓟马二代成虫的繁殖力均显著下降,成虫寿命显著缩短(40 mg/kg钾处理除外)。施钾后,苜蓿叶片可溶性糖含量、钾含量和糖氮比增大,游离氨基酸含量减少。相关关系分析表明,苜蓿叶片钾含量与牛角花齿蓟马幼期总存活率和成虫繁殖力无显著相关性,而苜蓿叶片可溶性糖含量和糖氮比均与3-4龄若虫存活率和繁殖力极显著负相关,与幼期总存活率呈显著负相关。【结论】施钾苜蓿对牛角花齿蓟马成虫产卵产生显著的排趋性;施钾提高了苜蓿叶片的可溶性糖含量及糖氮比,不利于若虫的生长发育,并使成虫寿命缩短、繁殖力下降,对牛角花齿蓟马产生了显著的抗生作用。     

苜蓿叶片水杨酸含量与其蓟马抗性的关系

采用不同抗蓟马特性的苜蓿品系,于不同蓟马虫口密度下测定苜蓿水杨酸含量和虫害程度,以明确苜蓿叶片水杨酸含量与其抗蓟马特性的关系.结果表明,苜蓿叶片游离态、结合态水杨酸含量均与苜蓿抗蓟马特性密切相关;高抗品系(抗蓟马品系)的水杨酸初始含量(0.539 mg·g-1)高于低抗品系(0.403 mg·g-1);与较低抗品系相比,高抗品系受害器官(叶)水杨酸含量随虫口密度和危害点面积的增大而增加相对缓慢,而随危害指数的增大而增加较快(3.84倍).可见,水杨酸主要是间接增强苜蓿对蓟马的抗性;高抗蓟马苜蓿品系能通过快速获得较高水杨酸含量来阻碍被危害伤口的扩大,降低其受危害程度,促使自身产量和品质提高.     

牛角花齿蓟马为害对苜蓿无性系根茎叶及同化产物分配的影响

为探索同化产物分配利用与苜蓿耐蓟马的关系,本试验以扦插的抗蓟马苜蓿无性系R-1和感蓟马苜蓿无性系 I-1为材料,研究不同虫口牛角花齿蓟马为害对苜蓿的抗性、根、茎和叶生长特性及可溶性糖含量的影响.结果表明: 随着虫口压力的增大,R-1和I-1苜蓿的受害指数升高;在相同虫口压力下,R-1苜蓿的受害指数显著低于I-1.受蓟马为害后,R-1和I-1苜蓿株高降低、叶面积减少、茎秆变细、节间长变短、节间数增加,根颈和主根直径加粗、侧根增多.在低虫口密度下,随虫口压力增大,R-1和I-1苜蓿地上部生物量增加,根冠比下降,分配到茎的生物量比例升高;在高虫口密度下,地上部生物量随虫口压力增大而减少,根冠比增加,分配到根系的生物量比例升高;R-1根冠比和茎生物量比例随虫口压力变化曲线的拐点均为每枝条5头,I-1根冠比和茎生物量比例随虫口压力变化曲线的拐点均为每枝条3头.在低虫口压力下,R-1苜蓿茎和叶中的可溶性糖含量随虫口压力增加而升高;在高虫口压力下,茎和叶中的可溶性糖含量随虫口压力增加而下降;根中可溶性糖含量随虫口压力增加持续下降.I-1根、茎和叶中的可溶性糖含量均随虫口压力增加持续下降.牛角花齿蓟马为害后,R-1根、茎和叶的农艺性状及抗性比I-1好,对同化产物的分配利用率高.     

牧草盲蝽危害对寄主植物体内营养物质含量及保护酶活性的影响

【目的】为了明确牧草盲蝽Lygus pratensis危害对不同寄主体内营养物质及保护酶的影响。【方法】采用分光光度法测定了牧草盲蝽偏好度不同的10种寄主植物(6种偏好寄主,偏好性依次为:灰绿藜Chenopodium glaucum马齿苋Portulaca oleracea反枝苋Amaranthus retroflexus紫花苜蓿Medicago sativa木地肤Kochia prostrata棉花Gossypium hirsutum; 4种非偏好寄主:碱蓬Suaeda glauca、天蓝苜蓿Medicago lupulina、田旋花Convolvulus arvensis和宽叶独行菜Lepidium latifolium)受其危害后叶片中叶绿素、可溶性糖和氨基酸含量以及保护酶活性。【结果】结果表明,受牧草盲蝽为害后,不同寄主植物叶片叶绿素含量均有所下降,其中反枝苋叶片叶绿素含量下降率最低,仅2.6%;紫花苜蓿叶片叶绿素含量下降率最高,达26.21%。可溶性糖含量变化各异,木地肤叶片可溶性糖含量下降率最高,达24.05%,且与对照(未受害株)间存在显著差异;灰绿藜叶片可溶性糖含量上升68.92%,与对照差异极显著。除反枝苋叶片游离脯氨酸含量下降38.87%,其余寄主叶片中游离脯氨酸含量均呈上升趋势。各寄主植物叶片中蛋白质含量均有所下降,反枝苋中下降率最低,仅2.96%。不同寄主中受害后叶片POD活性均呈增强趋势,马齿苋受害后叶片POD活性增幅最高,达74.23%。受害后寄主叶片CAT活性有增有减,灰绿藜、紫花苜蓿和田旋花叶片CAT活性增高,分别增加45.07%,30.95%和22.47%;马齿苋与天蓝苜蓿受害后叶片CAT活性下降显著。反枝苋、天蓝苜蓿受害后叶片SOD活性下降,其余寄主叶片中SOD活性上升,但均无显著差异。【结论】寄主受害后,叶片叶绿素含量、游离脯氨酸含量变化与牧草盲蝽偏好性具有较好的相关性,而可溶性糖和蛋白质含量及保护酶活性变化无规律性或无显著差异。     

紫花苜蓿内生和非内生根瘤菌多样性及共生差异

【背景】对根瘤菌多样性的研究有助于推进根瘤菌种质资源的利用。【目的】研究紫花苜蓿内生和非内生根瘤菌的表型和遗传多样性,比较菌株在5个苜蓿品种上的共生效应,验证根瘤菌群体共生效应由苜蓿品种决定的假设。【方法】从甘肃省白银会宁旱作区、兰州安宁灌区、武威凉州灌区3个栽培区域的陇中、清水、WL168HQ、甘农3号、甘农9号等紫花苜蓿品种中分离内生(植株种子、花、叶、茎、根表皮、根中柱和根瘤)和非内生(根际土壤和田间土壤)根瘤菌菌株,通过表型数值分类、 16SrRNA基因限制性片段长度多态性(Restrictionfragmentlengthpolymorphism,RFLP)、16S rRNA基因测序、持家基因多位点序列分型(Multilocus sequence typing,MLST),以及结瘤基因nodC和固氮基因nifH片段序列测定,研究紫花苜蓿根瘤菌的表型和遗传多样性,并采用主成分分析研究根瘤菌菌株在5个紫花苜蓿品种上的共生效应差异。【结果】共分离得到43株内生根瘤菌和10株非内生根瘤菌,叶片和花中没有分离到根瘤菌菌株。53株根瘤菌以及对照菌株R.GN5和S.12531表型特征数值分类聚为8个群,菌株表型多样性丰富。经16SrRNA-RFLP分析共形成22种RFLP分型组合,基因型Ⅰ分布最广泛(24),其次为基因型Ⅻ(5)、ⅩⅤ(5)和ⅩⅨ(3),其余16株菌各代表1种基因型,菌株遗传多样性丰富。16S rRNA基因测序和MLST分析将所有菌株划分为Rhizobiumradiobacter、R.rosettiformans和Ensifermeliloti。仅从7株E.meliloti代表菌株和对照菌株S.12531中扩增到nodC和nifH基因,说明E.meliloti菌株均能结瘤固氮。E.meliloti菌株G3L3接种甘农3号,LP3、LL1和LL2接种陇中,QL2接种清水,LL1、LL2和WLP2接种WL169HQ苜蓿均能显著促进植株的单株结瘤数、地上干重和粗蛋白含量。E.meliloti菌株接种甘农3号、甘农9号和清水苜蓿品种后所有参数值在PC1轴上分别聚在-1-1之间,在PC3轴上聚在-1.5-1.5之间;接种陇中和WL168HQ苜蓿的参数值较分散,PC1轴上分散在-1.5-4之间,PC3轴上分散在-3-4之间。【结论】紫花苜蓿内生和非内生根瘤菌菌株多样性丰富,表型和遗传多样性与其来源没有直接关系。菌株G3L3与甘农3号,LP3、LL1、LL2与陇中,QL2与清水、LL1、LL2、WLP2与WL169HQ苜蓿品种共生匹配和适应能力强。在甘农3号、甘农9号和清水紫花苜蓿品种上群体共生效应相似,在陇中和WL168HQ紫花苜蓿上共生效应差异明显。本研究内生和非内生根瘤菌菌株的群体共生效应根据苜蓿品种而定,根瘤菌菌株与苜蓿品种间的信号识别程度存在差异。     

紫花苜蓿叶输导组织解剖结构和光合特性对外源氮的响应

以紫花苜蓿品种‘甘农3号’和‘陇东苜蓿’为研究材料,采用室外(防雨网室)盆栽营养液砂培法,研究了2种氮素形态(NO3--N,NH4+-N)的5个氮素水平(0、105、210、315、420mg·L-1)处理对叶片输导组织解剖结构及光合特性的影响。结果显示:(1)与无氮处理相比,供氮处理下‘甘农3号’和‘陇东苜蓿’输导组织的解剖结构和光合特性发生明显变化,叶片输导组织维管束、木质部和韧皮部面积显著增大,导管数显著增多,净光合速率、气孔导度、叶面积和叶绿素含量均显著增加,且在210mg·L-1供氮水平下达到最大值。(2)2种氮素形态相比,‘甘农3号’和‘陇东苜蓿’叶片输导组织维管束面积、木质部面积、韧皮部面积、导管数、净光合速率、气孔导度、叶面积、叶绿素含量均表现为NH4+-N处理好于NO3--N处理。(3)2品种相比,叶片输导组织维管束面积、木质部面积、韧皮部面积、导管数、净光合速率、气孔导度、叶面积、叶绿素含量表现为‘甘农3号’大于‘陇东苜蓿’。研究表明,氮素能通过改善紫花苜蓿叶片输导组织的解剖结构和光合特性,促进紫花苜蓿光合作用;各处理中以NH4+-N、210mg·L-1表现最佳,维管束面积最大,木质部、韧皮部面积大且发育好,导管数最多,而且‘甘农3号’表现更优。     

中国主要苜蓿品种的产量性状及其多样性研究

对28个4龄苜蓿品种单株产量性状及其相关性和变异进行了研究．结果表明,品种间单株干物质产量及各产量性状存在显著差异,其中单株干物质产量最高和较高的分别是新疆大叶(452．8g·株^-1)和甘农3号(373．0g·株^-1);叶片最宽和最长者均为新疆大叶和甘农3号;单株枝条数增加最多是第3茬,3茬单株枝条数最高和较高的品种是新牧1号、图牧2号、肇东和北疆;苜蓿株高生长高峰期在第1茬,生长最快的品种为甘农3号和新疆大叶．相关分析表明,单株干物质产量与株高及枝条数等构成因素之间存在显著或极显著相关,其中1、3茬株高及3茬单株枝条数等性状相关最好,呈显著相关的品种达19～22个,且相关系数亦最高．产量性状变异分析表明,品种内变异大于品种间变异,前者占总变异的76．0％～93．8％,而后者仅占6．1％～24．0％．各性状变异程度表现依次为3茬单株枝条数>单株干物质产量>1茬单株枝条数>2茬单株枝条数>春季株高>3茬株高>2茬株高>叶宽>现蕾期株高>叶长>1茬株高．     

牛角花齿蓟马为害后苜蓿叶酚类物质和木质素含量的变化

为明确苜蓿中被蓟马为害后诱导的次生代谢物质含量的变化,以抗蓟马苜蓿R-1和感蓟马苜蓿I-1为材料,以每枝条0 头为对照,研究牛角花齿蓟马不同虫口密度(每枝条1、3、5、7 头)下苜蓿叶片中酚类物质和木质素含量的变化.结果表明: 蓟马为害7 d时,R-1和I-1叶中总酚、单宁和缩合单宁含量随虫口密度增大均升高,简单酚含量无显著差异;木质素含量显著高于对照.为害14 d时,R-1和I-1叶中总酚、单宁和缩合单宁含量随虫口密度增大均升高,简单酚含量无显著差异;木质素含量升高,且每枝条7 头密度下显著高于对照.为害21 d时,R-1和I-1叶中总酚、单宁和木质素含量随虫口密度增大均升高,在每枝条7 头密度下达到最高;R-1简单酚含量变化不显著,I-1简单酚含量显著升高.R-1和I-1叶中缩合单宁含量与对照无显著差异.抗感苜蓿中酚类物质与木质素含量在蓟马为害后均升高,R-1总酚、单宁和木质素含量的增加率均高于I-1.表明蓟马为害对苜蓿植株的总酚、单宁及木质素含量具有诱导效应,可以作为苜蓿抗蓟马的评价指标.     

西花蓟马取食对菜豆不同部位叶片防御基因表达的影响

【目的】本研究旨在探究锉吸式口器害虫西花蓟马Frankliniella occidentalis取食诱导的菜豆Phaseolus vulgaris木植株系统防御反应的分子机制。【方法】利用荧光定量PCR技术,检测西花蓟马分别在稳定取食菜豆植株2 h后的24,48,72和96 h菜豆植株不同部位(上部、中部和下部)叶片中茉莉酸信号转导途径和水杨酸信号转导途径防御相关基因脂氧合酶基因(LOX)、苯丙氨酸解氨酶基因(PAL)和β-1,3-葡聚糖酶基因(PR-2)相对表达量的变化。【结果】西花蓟马取食菜豆植株后,受害叶片及上部和下部健康叶片中LOX,PAL和PR-2均被显著诱导表达,均以受害叶片防御酶基因表达量的变化较大,并且表达量在相同叶片不同时间下的变化不同。中部受害叶片中LOX的相对表达量均显著高于未接虫的对照植株,并随西花蓟马为害时间的延长逐渐升高,在96 h时为对照的209.54倍;随着时间的延长LOX表达量在上部和下部健康叶片呈现升高-降低-升高的趋势。PAL的表达量在西花蓟马为害植株的中部受害叶片和上部健康叶片均于48 h时出现最大值,分别为对照的52.70倍和41.20倍;但在下部健康叶片于72 h时达到最大值,为对照的47.06倍。PR-2表达量在受害株的上部健康叶片于48 h时出现最大值,在中部受害叶片和下部健康叶片均于96 h时达到最大值,但在24 h时在下部健康叶片中受到抑制。【结论】西花蓟马取食能显著诱导菜豆植株茉莉酸和水杨酸信号转导途径相关防御酶基因LOX,PAL和PR-2的表达,并在菜豆植株不同部位叶片产生系统抗性。     

南美斑潜蝇幼虫为害对黄瓜叶片中水杨酸和茉莉酸的诱导作用

【目的】为揭示南美斑潜蝇Liriomyza huidobrensis (Blanchard)与其寄主相互作用的机理, 为利用诱导抗性控制南美斑潜蝇的发生为害奠定必要的基础。【方法】本文采用高效液相色谱法（HPLC）和超高效液相色谱法-质谱联用法（UPLC MS）, 分别测定了南美斑潜蝇幼虫为害对黄瓜叶片中茉莉酸（jasmonic acid, JA）和水杨酸（salicylic acid, SA）的诱导作用。【结果】南美斑潜蝇幼虫持续为害1 d后, 受害黄瓜叶片内JA含量即显著高于健康对照, 轻度受害处理和重度受害处理分别在第3天和第5天上升幅度最大, 分别比健康对照增加2.01倍和1.62倍; 而SA含量在3 d后才显著高于健康对照, 轻度受害处理和重度受害处理在第9天上升幅度最大, 分别比健康对照增加4.66倍和1.67倍; 轻度受害对JA和SA的系统诱导作用不明显, 而重度受害对JA和SA具有明显的系统诱导作用。【结论】南美斑潜蝇幼虫为害对黄瓜叶片内JA和SA具有诱导作用。     

A Unique Protease Cleavage Site Predicted in the Spike Protein of the Novel Pneumonia Coronavirus (2019-nCoV) Potentially Related to Viral Transmissibility

正Dear Editor,In December 2019, a novel human coronavirus caused an epidemic of severe pneumonia(Coronavirus Disease 2019,COVID-19) in Wuhan, Hubei, China(Wu et al. 2020; Zhu et al. 2020). So far, this virus has spread to all areas of China and even to other countries. The epidemic has caused 67,102 confirmed infections with 1526 fatal cases     

Curcuminoids as inhibitors of thioredoxin reductase: A receptor based pharmacophore study with distance mapping of the active site

Curcumin is the yellow pigment of turmeric that interacts irreversibly forming an adduct with thioredoxin reductase (TrxR), an enzyme responsible for redox control of cell and defence against oxidative stress. Docking at both the active sites of TrxR was performed to compare the potency of three naturally occurring curcuminoids, namely curcumin, demethoxy curcumin and bis-demethoxy curcumin. Results show that active sites of TrxR occur at the junction of E and F chains. Volume and area of both cavities is predicted. It has been concluded by distance mapping of the most active conformations that Se atom of catalytic residue SeCYS498, is at a distance of 3.56 from C13 of demethoxy curcumin at the E chain active site, whereas C13 carbon atom forms adduct with Se atom of SeCys 498. We report that at least one methoxy group in curcuminoids is necessary for interation with catalytic residues of thioredoxin. Pharmacophore of both active sites of the TrxR receptor for curcumin and demethoxy curcumin molecules has been drawn and proposed for design and synthesis of most probable potent antiproliferative synthetic drugs.     

Comparative morphology of the carpel in the Liliaceae: Hewardieae, Petrosavieae, and Tricyrteae

The young pistils in the melanthioid tribes, Hewardieae, Petrosavieae and Tricyrteae, are uniformly tricarpellate and syncarpous. They lack raphide idioblasts. All are multiovulate, with bitegmic ovules. The Petrosavieae are marked by the presence of septal glands and incomplete syncarpy. Tepals and stamens adhere to the ovary in the Hewardieae and the Petrosavieae but not in the Tricyrteae. Two vascular bundles occur in the stamens of the Hewartlieae and Tricyrtis latifolia. Ventral bundles in the upper part of the ovary of the Hewardieae are continuous with compound septal bundles and placental bundles in the lower part. Putative ventral bundles occur in the alternate position in the Tricyrteae and putative placental bundles in the opposite. position in the Petrosavieae. The dichtomously branched stigma in each carpel of the Tricyrteae is supplied by a bifurcated dorsal bundle.     

Enterovirus 71 3C proteolytically processes the histone H3 N-terminal tail during infection

Highlights
1. The N-terminal tail of histone H3 is specifically cleaved during EV71 infection.
2. Viral protease 3C is identified as a protease responsible for proteolytically processing the N-terminal H3 tail.
3. Our finding reveals a new epigenetic regulatory mechanism for Enterovirus 71 in virus-host interactions.     

Detection of EBV and HHV6 in the Brain Tissue of Patients with Rasmussen’s Encephalitis

Rasmussen’s encephalitis (RE) is a rare pediatric neurological disorder, and the exact etiology is not clear. Viral infection may be involved in the pathogenesis of RE, but conflicting results have reported. In this study, we evaluated the expression of both Epstein-Barr virus (EBV) and human herpes virus (HHV) 6 antigens in brain sections from 30 patients with RE and 16 control individuals by immunohistochemistry. In the RE group, EBV and HHV6 antigens were detected in 56.7% (17/30) and 50% (15/30) of individuals, respectively. In contrast, no detectable EBV and HHV6 antigen expression was found in brain tissues of the control group. The co-expression of EBV and HHV6 was detected in 20.0% (6/30) of individuals. In particular, a 4-year-old boy had a typical clinical course, including a medical history of viral encephalitis, intractable epilepsy, and hemispheric atrophy. The co-expression of EBV and HHV6 was detected in neurons and astrocytes in the brain tissue, accompanied by a high frequency of CD8⁺ T cells. Our results suggest that EBV and HHV6 infection and the activation of CD8⁺ T cells are involved in the pathogenesis of RE.     

Perinatal Vertical Transmission of Chikungunya Virus in Ruili,a Town on the Border between China and Myanmar

正Dear Editor,Chikungunya virus (CHIKV), an arbovirus in the family of Togaviridae, genus Alphavirus, is transmitted by the A.aegyptii or A. albopictus mosquito, and causes disease in humans characterized by fever, rash, and arthralgia (Silva and Dermody 2017; Suhrbier 2019). It was first reported in 1953 in Tanzania, and caused only a few outbreaks and sporadic cases in Africa and Asia in last century. However, in the epidemic in 2004, CHIKV acquired mutations that conferred enhanced transmission by the A. albopictus mosquito(Schuffenecker et al. 2006). Since then, it has successively caused outbreaks in Africa, the Indian Ocean, South East Asia, the South America, and Europe (Zeller et al. 2016).     

Development of a Novel Reverse Transcription Loop-Mediated Isothermal Amplification Method for Rapid Detection of SARS-CoV-2

In conclusion, the novel visual RT-LAMP assay is a simple, rapid, and sensitive approach for detection of SARS-CoV-2, and it is ready for application in primary care and community hospitals or health care centers, and even patients' own houses in response to the current SARS-CoV-2 epidemic because the assay does not require sophisticated equipment and skilled personnel. Furthermore, it is also ready to be used in fields for screening samples from wild animals and environments to facilitate the identification of potential intermediate hosts that mediate the cross-species transmission of SARS-CoV-2 from bats to humans.